A WCDMA (Wideband Code Division Multiple Access) or CDMA (Code Division Multiple Access) combined cell comprises a number of cell portions, each cell portion having one or more antenna units for DL (Downlink) and UL (Uplink) radio links. The DL in all cell portions transmits the cell information and an individual CPICH (Common Pilot Channel) in each cell portion defines that cell portion's coverage, where the cell portions together form the cell and the cell coverage. The DL power relative to cell portion CPICH is the same in all portions. The DL channels towards one specific user terminal are transmitted in all cell portions independent of whether the user terminal can benefit from the signal or not. In UL, the RBS (Radio Base Station) periodically searches for the user terminal signal in all portions and receives the UL signal from the user terminal in portions where significant power is detected.
A problem in such a configuration with combined cells is that the RBS do not know whether a user terminal benefits from the DL power in a cell portion or not. There is no possibility for the user terminal to distinguish between signals received from different cell portions. The signals are experienced as multipath signals by the user terminal and there is one power control loop adjusting the received multipath DL power.
To effectively use available DL power and to mitigate inter/intra cell interference, it is advantageous if the DL to user terminal is transmitted only in the cell portions where the user terminal has a sufficient benefit of the provided power.
It is thus desirable to be able to detect if a user terminal can receive and benefit from a certain DL radio link in a certain cell portion to a relatively high extent of reliability.